Hydraulic jar



NOV 16, 1965 o. MORRISETT ETAL 3,217,31i7

HYDRAULIC JAR Filed Jan. l5, 1963 2 Sheets-Sheet 1 Nov. 16, 1965 o, 1 MoRRlsl-:TT ETAL 3,217,817

HYDRAULIC JAR 2 Sheets-Sheet 2 Filed Jan. l5, 1963 TE S N wm EH. N um mmm m LE VO T 115 mw mmm A a Q .2 5 10m L A n. l, f .4. z f Owf/M/ Y B 4 N m United States Patent O 3,217,817 HYDRAULIC JAR O. L. Morrisett and Walter E. Hyde, Duncan, Okla., as-

signors to Halliburton Company, Duncan, Okla., a corporation of Delaware Filed Jan. 15, 1963, Ser. No. 251,701 3 Claims. (Cl. 175-297) This invention relates to hydraulic jars of the type wherein the jar slowly lengthens as the drill pipe attached thereto is stretched, then suddenly releases to produce an upward impact.

A principal object of this invention is to provide a hydraulic jar which incorporates a simple, yet effective, valve mechanism and bypass arrangement whereby the hydraulic fluid is initially metered, causing slow movement of jar anvils to permit stretching of the well pipe until the valve mechanism opens, whereupon rapid iiow of the hydraulic fiuid occurs to cause a hammer blow between the anvil elements of the jar, and whereby, on the return stroke, the valve mechanism is bypassed to ensure free fiow of the hydraulic fiuid to its initial chamber.

A further object of this invention is to provide a hydraulic jar which is capable of repeated operation, and which may be adapted to deliver a downward as well as an upward blow.

With the above and other objects in View as may appear hereinafter, reference is directed to the accompanying drawings in which:

FIGURE l is a longitudinal, sectional view of the hydraulic jar showing the upper portion thereof, the parts of the jar being shown in the positions assumed after the initial movement of the jar on its jarring stroke;

FIGURE 2 is a longitudinal, sectional View continuing from FIGURE 1, the upper portion of FIGURE 2 overlapping the lower portion of FIGURE 1;

FIGURE 3 is a longitudinal, sectional view of the hydraulic jar similar to FIGURE 1, showing the jar in the position assumed on completion of the jarring stroke;

FIGURE 4 is a fragmentary, longitudinal, sectional view of the jar showing portions thereof as they appear during the return stroke of the jar;

FIGURE 5 is an enlarged, transverse, sectional view taken through 5-5 of FIGURE 4;

FIGURE 6 is a transverse, sectional view taken through 6-6 of FIGURE 3.

The hydraulic jar is provided at its upper end with a coupling 1 internally screw-threaded for connection to a tubing string not shown. The lower end of the coupling is also internally screw-threaded to receive a stem 2. The major portion of the stem below the coupling is square or hexagonal in cross section. Its lower end is enlarged to form a piston 3. An anvil shoulder 4 is formed between the stem 2 and the piston 3.

Fitted over the stem 2 is anvil housing or cylinder 5 having a diameter to receive the piston 3. The upper end of the anvil housing 5 is provided with a square or hexagonal opening corresponding to the stem 2 so that torsional loads may be transmitted from the stem 2 to the anvil housing 5. Internally, the upper end of the anvil housing 5 forms an anvil fiange 6 which is engageable by the anvil shoulder 4, as indicated in FIGURE 3.

A mandrel 7 is screw-threaded into the lower end of the piston 3. The lower end of the mandrel 7 terminates in a second piston 8. The stem 2 and the mandrel 7 are provided with coaxial longitudinal bores 9 and 10, respectively.

The lower end of the anvil housing 5 is internally screwthreaded for connection to a tubular valve body member 11. The valve body member is externally screwthreaded at its lower end for connection to a lower hous- JCC ing or cylinder 12. The lower end of the housing 12 is externally screw-threaded for connection to a tubing string indicated by broken lines in FIGURE l.

The pistons 3 and 8 are provided with seal rings 13 and 14. Adjacent the internal anvil fiange 6 the anvil housing 5 is provided with one or more bleed ports 5a.

The piston 3, mandrel 7, housing 5, and valve body member 11 form a hydraulic fluid-receiving -chamber 30. Similarly, the piston 8, mandrel 7, housing 12, and valve body member 11 form hydraulic fluid-receiving chamber 31.

The lower portion of the valve body member 11 is counterbored and screw-threaded to receive a liner 15, the internal diameter of which is equal to the normal internal diameter of the valve body member 11. The shoulder formed by the upper end of the counterbore and the upper extremity forms limit stop 16 and 17, respectively, between which is mounted a slide valve 18. The slide valve is in the form of a ring dimensioned to grip the mandrel 7 with sufiicient force so as to move with the mandrel unless restrained by either stop 16 or 17.

Midway in the region between the stops 16 and 17 the valve body member 11 is further enlarged to form an annular valve cavity 19. The upper extremity of this cavity is shaped to form, with the slide valve 18, an O- ring channel 20 which receives an O-ring 21. The lower side of the valve cavity 19 is provided with a ring of downwardly converging backfiow passages 22. The ring formed by these passages at their ends intersecting the valve cavity 19 is of greater diameter than the O-ring 21.

The upper portion of the liner 15 forms with the confronting walls of the valve body member 11 an annular backfiow passage 23 communicating with the ring of converging backflow passages 22. Ports 24 communicate between the annular backfiow passage 23 and the bore of the liner 15. The bore of the liner 15 and the normal bore of the valve body member 11 are dimensioned to loosely receive the mandrel 7 so as to define therewith an annular forward or upward fiow passage 25 communieating between the ends of the valve body member 11.

The mandrel 7 is provided with an offset bore 26 eX- tending downwardly from its upper end. The offset bore receives a metering pin 27 for the purpose of restricting the effective area of the offset bore. The offset bore 26 is intersected near its upper end immediately below the piston 3 by a side port 28. The lower end of the offset bore 26 is intersected by a side slot 29 of greater axial length than the slide Valve 18. If desired, additional bores 26 and metering pins 27 may be provided.

Operation of the hydraulic jar is as follows:

The hydraulic jar and a fishing tool are connected to the lower end of a tubing string, whereupon the tubing string is lowered into the well and manipulated to cause the fishing tool to engage the oil well fish which it is desired to remove. By reason ofthe drive connection provided between the stem 2 and the upper housing S and the tightly made-up screw-threaded connections between the parts of the hydraulic jar, it is possible to manipulate the fishing tool in the conventional manner.

The cavities within the hydraulic jar between the piston 3 and the piston 8 contain an incompressible liquid selected to have the desired viscosity at the temperature encountered in the well bore.

Initially, the hydraulic jar is fully telescoped so that the lower end of the piston 3 rests on the upper end of the valve body member 11. In this condition, the slide valve 18 and the O-ring 21 are in the position shown in FIG- URE 4.

To produce a jarring action, tension is applied to the drill string. This has the initial effect of lifting the mandrel 7 and slide valve 18 until the slide valve engages the upper stop 16. Also the O-ring 21 is moved upwardly into the O-ring channel 20. This is the condition shown in FIGURES 1 and 2. After this condition is obtained, the rate at which the mandrel 7 may move upwardly is dependent upon the rate at which fluid may ilow from the region below the valve body member 11 to the region above the valve body member as determined by the offset bore 26 restricted by the metering pin 27. Continued application of tension to the upper end of the drill string under these conditions causes the drill string to stretch.

The mandrel 7 continues to move upward slowly until the slot 29 bridges the slide valve 18, whereupon the hydraulic fluid flows readily upwardly through the annular passage 25 and slot 29 into the upper chamber above the valve body member 11; and, as a consequence, the anvil shoulder 4 delivers a hammer blow against the anvil ange 6.

To repeat the jarring action, tension on the tubing string is released and the tubing string lowered so as to return the piston 3 to its lower initial position. In doing so, the slide valve 18 moves to its lower position shown in FIGURE 4 and the O-ring 21 likewise moves downward, so that the hydraulic fluid may readily flow back to the chamber below the valve body member 11 and thus utilize the passages 22 and 23 and the ports 24.

While the particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modications may be made without departing from this invention in its broader aspects; and therefore the aim in the appended claims is to cover `all such changes and modifications as -fall within the true spirit and scope of this invention.

What is claimed is:

1. A hydraulic jar, comprising: a pair of coaxial cylinders each having a piston slidably mounted therein, a tubular valve body connecting said cylinders, an axially movable mandrel extending through said valve body and connecting said pistons, said pistons and cylinders, mandrel, and valve body forming -a pair of hydraulic Huid receiving chambers at opposite axial ends of said valve body, mutually engageable anvil elements provided on one of said pistons and a corresponding cylinder, said valve body having a backflow passage for movement of hydraulic fluid between said chambers in a direction to permit separation of said anvil elements, said valve body having axially spaced limit stops and having lan O-ring seat therebetween, a slide valve frictionally gripping said mandrel and movable axially therewith between said limit stops, an O-ring encircling said mandrel and movable axially therewith into an out of engagement with said seat to close and open said backilow passage, restricted flow means incorporated in said mandrel and bypassing said slide valve to permit slow approach of said anvil elements when said backiiow passage is closed, and relatively unrestricted flow means also incorporated in said mandrel and movable into position to bypass said slide valve after a predetermined slow approach of said anvil elements, thereupon to permit fast approach of said anvil elements into impact engagement.

2. A hydraulic jar, comprising: a pair of coaxial cylinders each having a piston slidably mounted therein, a tubular valve body connecting said cylinders, an axially movable mandrel extending through said valve body and connecting said pistons, said pistons and cylinders, mandrel, and valve body forming a pair of hydraulic fluid receiving chambers at opposite `axial ends of said valve body, mutually engageable anvil elements provided on one of said pistons and a corresponding cylinder, said valve body having a backflow passage for movement of hydraulic tluid between said chambers in a direction to permit separation of said anvil elements, said valve body having axially spaced limit stops and having an O-ring seat therebetween, a slide valve frictionally gripping said mandrel and movable axially 'therewith between said limit stops, an O-ring encircling said mandrel and movable axially therewith into `and out of engagement with said seat to Close and open said backow passage, means forming a restricted flow passage in said mandrel and bypassing said slide valve to permit slow approach of said anvil elements when said backi'low passage is closed, the mandrel having an external axial slot providing relatively unrestricted ow passage and movable into position to bypass said slide valve after a predetermined slow approach of said anvil elements, thereupon to permit fast approach of said anvil elements into impact engagement.

3. A hydraulic jar, comprising: la pair of coaxial cylinders each having a piston slidably mounted therein, a tubular valve body connecting said cylinders, an axially movable mandrel extending through said valve body and connecting said pistons, said pistons and cylinders, mandrel, and valve body forming a pair of hydraulic uid receiving chambers at opposite axial ends of said valve body, mutually engageable anvil elements provided on one of said pistons and a corresponding cylinder, said valve body having a backow passage for movement of hydraulic fluid between said chambers in a direction to permit separation of said anvil elements, said valve body having axially spaced limit stops and having an O-ring seat therebetween, a slide valve frictionally gripping said mandrel and movable axially therewith between said limit stops, an O-ring encircling said mandrel and movable axially therewith into and out of engagement with said seat to close and open said backow passage, an external axial slot on the mandrel, means `forming a restricted passage on the mandrel communicating with said slot, the restricted passage being positioned to bypass the slide valve to permit slow approach of said anvil elements, and the external axial slot being positioned to bypass the slide valve to permit yfast approach of said anvil elements into impact engagement.

References Cited bythe Examiner UNlTED STATES PATENTS 2,180,223 1l/l939 Collett 175-297 2,987,129 6/1961 Webb 175-297 CHARLES E OCONNELL, Primary Examiner. 

1. A HYDRAULIC JAR, COMPRISING: A PAIR OF COAXIAL CYLINDERS EACH HAVING A PISTON SLIDABLY MOUNTED THEREIN, A TUBULAR VALVE BODY CONNECTING SAID CYLINDERS, AN AXIALLY MOVABLE MANDREL EXTENDING THROUGH SAID VALVE BODY AND CONNECTING SAID PISTONS, SAID PISTONS AND CYLINDERS, MANDREL, AND VALVE BODY FORMING A PAIR OF HYDRAULIC FLUID RECEIVING CHAMBERS AT OPPOSITE AXIL ENDS OF SAID VALVE BODY, MUTUALLY ENGAGEABLE ANVIL ELEMENTS PROVIDED ON ONE OF SAID PISTONS AND A CORRESPONDING CYLINDER, SAID VALVE BODY HAVING A BACKFLOW PASSAGE FOR MOVEMENT OF HYDRAULIC FLUID BETWEEN SAID CHAMBERS IN A DIRECTION TO PERMIT SEPARATION OF SAID ANVIL ELEMENTS, SAID VALVE BODY HAVING AXIALLY SPACED LIMIT STOPS AND HAVING AN O-RING SEAT THEREBETWEEN, A SLIDE VALVE FRICTIONALLY GRIPPING 